Distribution of selected metals in bottom sediments, water, clams, tubificid mnnelids, and fishes of the Middle Illinois River

This study was designed to assess the potential application for further research of metal contamination in a large mid-western river that is utilized by industries and certain cities as a source of potable water as well as for sewage disposal. Analyses were made for thirteen metals in bottom sediments, twelve in water, and ten in tubificid worms, clams, and fishes. The study revealed that the ten metals, for which analyses were made in biota, do not concentrate along successive tropic levels as is the case with pesticides. Organisms such as clams and worms that inhabit the mud or mud-water interface where metal concentrations were observed to be the highest, exhibited the highest metal concentrations. At higher trophic levels, however, concentrations were lower, with fishes that are primarily carnivorous in nature exhibiting the lowest concentrations. The problem of metal contamination in aquatic systems is just now being recognized as a potential hazard to human health while the degree to which aquatic biota are affected remains speculative. This study, basically a pilot study, outlines procedures by which similar studies can be made and provides data that others may use in assessing the degree of metal contamination in multiple use rivers.U.S. Department of the InteriorU.S. Geological SurveyOpe

Sediment oxygen demand and its effect on dissolved oxygen in a cutoff meander of the Kaskaskia River

This study was designed to assess the relationship of sediment oxygen demand and dissolved oxygen in a cutoff meander of the Kaskaskia River. The results of the study should be useful to agencies such as Departments of Conservation, Corps of Engineers and the Environmental Protection Agency when assessing the impact of stream channelization on cutoff meanders of channelized streams. Cross-sectional profiles were used to determine area and total water volume in the meander. When stagnant or no-flow conditions prevailed, anoxic conditions created by sediment oxygen demand were observed in a significant part of the water in the meander. When no-flow conditions prevailed during summer months, as much as 25% of the water in the meander became anoxic while 65% fell below 5.0 mg/l. Sediment oxygen demand rates were more closely related to temperature than to sediment consistency or benthic macroinvertebrate numbers. Ambient sediment oxygen demand measured during the summer was almost three times greater than demand measured during the fall. While sediment oxygen demand in the channelized portion of the river was higher than in some stations in the meander, reaeration resulting from flowing water in the channel was sufficient to prevent anoxic conditions from developing.U.S. Department of the InteriorU.S. Geological SurveyOpe

Dynamics of manganese, cadmium, and lead in experimental power plant ponds

This study was designed to determine the effect of heated power plant cooling water on the compartmentalization of manganese, lead and cadmium in experimental ponds. Caged channel catfish and green sunfish were kept in an experimental pond and a control pond. Periodically, whole fishes, gill, heart, kidney, liver and musculature were analyzed for the three metals. Concentrations of the three metals in fishes were not affected by the temperature differential maintained during the study. There was no correlation in concentrations of cadmium and lead with age (weight and length) of fishes but manganese concentrations declined slightly with age. The water component of the system contained the lowest concentration of the metals with sediments acting as a characteristic sink. Concentrations of the three metals in water and sediments of the ponds were unaffected by heat inasmuch as concentration differences between ponds were not significant at the .05 level. Aquatic organisms such as snails, fingernail clams, leeches, tubificid annelids and dragonfly nymphs exhibited concentrations of cadmium higher than sediments while snails and duckweed more closely reflected concentrations of manganese in sediments. Tubificid worms and leeches more closely reflected lead concentrations in sediments while fingernail clams and snails exhibited higher concentrations.U.S. Department of the InteriorU.S. Geological SurveyOpe

Dust in Supernovae and Supernova Remnants I : Formation Scenarios

Supernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.Peer reviewe

Dust in Supernovae and Supernova Remnants II: Processing and survival

Observations have recently shown that supernovae are efficient dust factories, as predicted for a long time by theoretical models. The rapid evolution of their stellar progenitors combined with their efficiency in precipitating refractory elements from the gas phase into dust grains make supernovae the major potential suppliers of dust in the early Universe, where more conventional sources like Asymptotic Giant Branch (AGB) stars did not have time to evolve. However, dust yields inferred from observations of young supernovae or derived from models do not reflect the net amount of supernova-condensed dust able to be expelled from the remnants and reach the interstellar medium. The cavity where the dust is formed and initially resides is crossed by the high velocity reverse shock which is generated by the pressure of the circumstellar material shocked by the expanding supernova blast wave. Depending on grain composition and initial size, processing by the reverse shock may lead to substantial dust erosion and even complete destruction. The goal of this review is to present the state of the art about processing and survival of dust inside supernova remnants, in terms of theoretical modelling and comparison to observations